Lehre



2 Sheets-Sheet 1 O. LEHRE CALCULATOR June 25, 1957 Filed April 30. 195.4

o. LEHRE `une 25, 1957 CALCULATOR 2 Sheets-Sheet 2 Filed April 30, 1954 INVENTOR 2 orro LEHRE BY "@QMQJ L7M; t @w AT 7' ORNEYS United States PatentO CALCULATOR Otto Lehre, Springfield, N. I., assignor to Sterling Plastics Co., Union, N J., a corporation of New Jersey Application Apiii so, 1954, sei-iai No. 426,807

6 Claims. (Cl. 23S-74) The present invention relates to improvements in calculators, particularly of the type having dials which are manipulated to introduce the problem into the calculator and then indicate the result of the calculation.

It is an object of the invention to provide a calculator of the described character made up of a relatively small number of parts which are easily assembled together to forma simple and compact structure capable of accurate addition and subtraction.

Another object is to provide a calculator of the described character capable of performing calculations involving a plurality of digits, and wherein identical and cooperating assemblies of parts are included for each of the digits, with such parts being simple in configuration as to be susceptible of manufacture from molded, or otherwise formed, plastic resin, thereby to make feasible the inexpensive, mass production of the calculator.

Still another object is to provide a calculator of the described character having means embodied therein to prevent over-running or incorrect indexing of the successive dials during accumulative angular displacement of the dials in response to rotation of the preceding dial.

A further object is to provide a calculator of the described character which is so simple and compact in construction as to make possible the mounting thereof in the cover of a box, for example, for pencils and the like.

In accordance with the present invention, the' possibility of inexpensively manufacturing and assembling the various parts of the calculator is realized by providing an elongated, relatively flat casing including a top having suitable openings through which the dials can be manipulated and the totals viewed and a bottom having projections extending perpendicular thereto and on which al1 parts of the calculator, other than the casing, are mounted from above, thereby facilitating the formation of the casing from molded, or otherwise formed, plastic resin and the assembly of the parts on said projections of the bottom prior to closing of the casing by the top thereof.l

A calculator according to this invention includes a plurality of independently rotatable dials, each corresponding to a digit in the numerical result of a calculation, which are mounted in a common plane with accumulating means co-acting between adjacent dials to effect accumulative angular displacement of one of the adjacent dials in response to rotation of the other. The accumulating means include a transmission gear rotatably mounted between the axes of any two adjacent dials, at least one of which has a gear mounted thereon and in mesh with said transmission gear so that the one dial and the transmission gear rotate together. The transmission gear carries a circularly arranged series of spaced indexing elements which project into the path' of rotation of a driving abutment on the other of the adjacent dials, so` that the abutment engages one of the indexing elements to angularly displace the transmission gear and ice said one dial upon each complete revolution of said other dial. Thus the successive dials of the series may accumulate digits in orders of units, tens, hundreds, etc. and digits of any order may be added or subtracted and properly accumulated by the rotation of the corresponding dial.

In order to assure the proper degree of angular displacement of one dial in response to rotation of another, control means are provided which include a rockably mounted retainer or pawl having one end formed to engage between adjacent indexing elements on the transmission gear and another end that coacts with a projection or projections on said other dial of any two adjacent dials. The projection or projections have a fixed angular relation to the abutment on the same dial, and the several parts are so related that each action of the abutment to displace the coacting transmission gear is accompanied by a rocking of the pawl out of the path of the indexing elements on that gear yet is followed by positive movement of the pawl into an active position in which it blocks further angular displacement of the transmission gear.

Another feature of the invention resides in the provision of a single spring means cooperating with the dials in two adjacent digit assemblies of a calculator of the kind described above and preventing inadvertent rotation of said dials from registering positions.

The foregoing, and other objects, features and advantages of the invention, will be apparent in the following detailed description of an illustrative embodiment presented by way of example and toY be read in connection with the accompanying drawings forming a part hereof, and wherein:

Fig. l is a top plan view of a calculator embodying the present invention, with a portion of the casing thereof being removed to show the internal mechanism;

Fig. 2 is a fragmentary, enlarged View of a portion of Fig, l with one of the dials included in the mechanism being partly broken away and in section to illustrate the cooperation thereof with other parts of the mechanism and with a pawl included in the mechanism being shown in broken lines in its released position;

Fig. 3 is a longitudinal, sectional View taken along the line 3-3 of Fig. 2;

Fig. 4 is a longitudinal, sectional view taken along the line 4 4 of Fig. 2;

Fig. 5 is a bottom plan view of one of the dials included in the calculator embodying the invention;

Fig. 6 is a side elevational view of the dial of Fig. 5;

Fig. 7 is a bottom plan view of a transmission gear included in the illustrated embodiment of the invention; and

Fig. 8 is a side elevational View of the transmission gear of Fig. 7.

Referring to the drawings in detail, and initially to Figs.

1 to 4, inclusive, a calculator embodying the present invention is there illustrated and generally identified by the reference numeral 1t). Calculator 10 includes a hollow, elongated and relatively flat casing 11 defined by a top wall 12, bottom wall 13 and side wall 14 maintaining the walls 12 and 13 in spaced apart relationship.

The calculator 1li illustrated in Fig. 1 is intended for the performance of calculations involving numbers of no more than four digits, but it is to be understood that calculators for more or less digits may be constructed in accordance with the invention. The calculator 10 includes a manipulating and indicating dial for each of the digits, and these dials are generally identified by the reference numerals 15, 15a, 15b and 15e, respectively.V

.o The several dials are mounted in a row within casing 11 at locations which are spaced apart longitudinally for rotation about respective stub shafts 16 projecting from bottom wall 13.

Each of the dials includes a substantially circular disc 17 (Figs. 2 and 5) having ten total iigures, 0 to 9, printed, cut or otherwise formed on the upper surface thereof so as to be selectively visible through a related viewing opening or window 13 formed in upper wall 12 of the casing (Fig. l). The upper surface of each disc 17 is also provided with a circularly arranged series of ten spaced apart pockets or recesses 19 which are preferably disposed radially inward with respect to the numerals O to 9 and which register with, and are accessible through, a related substantially circular slot 29 formed in top wall 12 of the casing. A neck or portion 21 extends radially across each slot 20 to support the central portion 22 of the top wall encircled by slot 2i) and also to serve as a stop for an operating stylus or pencil inserted in a selected one of the pockets 19 for effecting rotation of the dial. The neck or stop 21 preferably is as wide as the distance between the successive pockets 19, and the numerals to 9 on the upper surface of disc 17 are circumferentially disposed relative to pockets 19 so that a selected one of the numerals will register with the opening 18 when a stylus or pencil engaged in a related Vone of pockets 19 comes into contact with one side or the other of Vstop 21.

Addition and subtraction numerals 0 to 9 are printed, cut or otherwise formed on the upper surface of top wall 12 along each of the circular slots 20. The addition numerals are placed consecutively anti-clockwise along the outer edge of the related slot 20 and starting from the stop 21; while the subtraction numerals are placed consecutively clockwise on the top wall portion 22 along the inner edge of the related slot 29 and also starting from the stop 21.

ln order to provide for the accumulative angular displacement of each of the dials 15a, 15b and 15e in response to the rotation of the preceding dials 15, 15a and 15b, respectively, each of the dials includes a spur gear 23 (Figs. 2, 5 and 6) disposed below disc 17 and preferably formed integral with the latter. Transmission gears 24, 24a and 24h are disposed between the successive spaced apart dials and are rotatably mounted on suitable stub shafts 2S projecting from bottom wall 13 of the casing. The several transmission gears are arranged so that gear 24 meshes with gear 23 of dial 15a, gear 24a meshes with gear 23 of dial 15b and gear 24h meshes with gear 23 of dial 15C. While the teeth of gears 24, 24a and 24b pass under the discs 17 of dials 15, 15a and 15b, respectively, it is to be noted that the above enumerated transmission gears do not mesh with the gears 23 of the dials disposed to the right thereof, as viewed in Figs. 1, 2, 3 and 4 of the drawings.

Each of dial gears 23 and transmission gears 24, 24a and 2419 (Figs. 2, and 7) preferably has ten teeth, and the several dials and transmission gears carry cooperating members effective to produce the angular displacement of the transmission gear and of the dial driven thereby through one-tenth of a revolution, that is, through an angle of 36 degrees, in response to the rotation of the dial disposed to the right, as viewed in the drawings, through a complete revolution. Thus, the rotation of dial through a complete revolution is effective to produce a 36 degree displacement of the dial 15a; rotation of dial 15a through a complete revolution is effective to produce a 36 degree angular displacement of dial 15b; and rotation of 15b through a complete revolution is effective to produce a 36 degree angular displacement of dial 15C. In order to produce such accumulative angular displacement of the dials in response to rotation of the preceding dials, each of the transmission gears 24, 24a and 24h is formed with a circularly arranged series ofpins 26 projecting upwardly therefrom in radial alignment with the teeth, and a driving abutment 27 depends from disc 17 of each of the dials to engage the pins 26 of the transmission gear disposed to the left of the related dial, as viewed in Figs. l, 2, 3 and 4 of the drawings. Thus, the driving abutment 27 of dial 15 is engageable with pins 26 of transmission gear 24, the driving abutment of dial 15a is engageable with pins 26 of transmission gear 24a, and the driving abutment of dial 15b is engageable with pins 26 of transmission gear 24b. Preferably, as shown in Fig. 2, the pins 26 are disposed adjacent the bases of the teeth of the related transmission gear, while the driving abutment 27 terminates, at its inner end, at the addendum circle of the gear 23 of the related dial so as to avoid contact with the pins 26 of the transmission gear meshing with the gear 23 of the related dial.

In order to yieldably hold the several dials against inadvertent angular displacement from positions wherein selected ones of the'numerals on the top surfaces of the related discs 17 are exposed at the openings 18 in top wall 12, spring detents 28 and 28a are mounted within casing 11 and are engageable with gears 23 of the dials. In the illustrated embodiment of the invention, spring dew tent 28 cooperates with gears 23 of the dials 15 and 15a whilerspring detent 28a cooperates with the gears 23 of dials 15b and 15C. As seen in Fig. 2, each of spring detents 28 and 23a includes an elongated strip of spring metal interlaced between a central post 29 and two lateral posts 30 Yspaced from the central post, said posts extending from lbottom 13 of the casing to support the spring detent, while the opposite ends of the spring detents are provided with bent noses 31 engageable between the successive teeth of the adjacent gears 23 and urged radially inward by the resilience of the detent toward the centers of rotation of the gears. Thus, at any time, the detents 28 and 28a are effective to yieldably hold the related dials in angular positions wherein one of the numerals on the top surface of each of the dials will be completely exposed at the related opening 18.

In accordance with the present invention, control means are associated with each of transmission gears 24, 24a and 24b to ensure that contact between the driving abutment or accumulating finger 27 of the adjacent dial with a pin 26 of the related transmission gear produces an angular displacement of the latter of only 36 degrees or one-tenth of a revolution. In the illustrated embodiment of the invention, such control of the step-by-step rotation of the transmission gears is eliected by rockable retainers or pawls 32, 32a and 32b which are respectively associated with the transmission gears 24, 24a and 2411. Each of the pawls is rockably mounted, intermediate its ends, on a stub shaft 33 projecting upwardly from bottom Wall 13 of the casing. At one end, each pawl is provided with a nose 34 having converging or inclined side edges and adapted to engage between successive pins 26 on the related transmission gear. Pawls 32, 32a and 32b are respectively actuated by dials 15, 15a and 15b, and such actuation is achieved by a follower portion 35, at the end of each pawl remote from nose 34, engageable by projections 36, 37, 38 and 39 extending from the periphery of the dial to the right, as rviewed in the drawings, of the related transmission gear. As seen in Fig. 2, cam-like projections 36 and 37 are adjacent to each other and projections 38 and 39 are also adjacent to each other but spaced circumferentially from the projections 36 and 37 thereby to provide a recess 40 between the projections 37 and 38. The projections 36 land 37 are operative to actuate the related pawl 32, 32a or 32b during rotation of the related dial in the direction for addition, lthat is, during clockwise rotation of the dial, while the projections 38k and 39 actuate the related pawl during rotation of the dial in the direction lforsubtraction, that is, during counter-clockwise rotation. 'Ihe projections 36, 37, 38'and 39 are arranged on the periphery of the dial so that during engagement between the abutment 27 and -on'e -oftbepins -26 ofv'an adjacent @remar transmission gear, radially opening recess 40 is registered with follower portion 35 of the related pawl, to permit movement of the follower portion radially inward toward the axis of rotation of the dial and corresponding radially outward movement of the nose 34 away from the axis of rotation of the transmission gear.

Normally, pawls 32, 32a and 32b are disposed as shownin Figs. 1 and 2, with the noses 34 thereof positioned between two successive pins 26 on the related transmission gear thereby to position the latter and the dial having the gear 23 with which the transmission gear is in mesh. However, when the transmission gear is angularly displaced by contact of the driving abutment 27 of the dial to the right thereof, as viewed in Figs. 1 and 2, one or the other of the pins 26 between which nose 34 engages rides against the confronting inclined side edge of nose 34 and rocks the pawl in the clockwise direction to the position shown in broken lines on Fig. 2 and there identified by the reference numeral 32'. Thus, nose 34 of the pawl is displaced radially out of the path of travel of the pins 26 to permit angular displacement of the transmission gear, and during such angular displacement of the transmission gear, follower portion 35 of the paWl engages in the outwardly opening recess 40 at the periphery of the dial. As soon as the transmission gear has been angularly displaced to an extent suicient to bring the pin 26, mentioned above as riding against the inclined side edge, past the apex of nose 34, one or the other of the cam-like projections 37 or 38, depending upon the direction or rotation of the dial, strikes against follower portion 35 to displace the latter radially outward with respect to the axis of rotation of the dial and thereby rocks the associated pawl in the counter-clockwise direction, as viewed in Fig. 2, to at least partially introduce nose 34 of the pawl between the next successive pins 26 on the transmission gear for preventing over-running or jumping of the latter. Further rotation of the dial brings either the projection 36 or the projection 39, depending upon'the direction of rotation of the dial, into engagement with the follower portion 35 of the related pawl. e Since the projections 36 and 39 extend radially outwardk further than the projections 37 and 38, engagement of vthe projection 36 or the projection 39 with the follower portion 35 produces additional counter-clockwise rocking of the pawl thereby to complete movement of the nose 34 radially inward toward the axis of rotation of the related transmission gear to its normal position wherein the converging side edges of nose 34 engage the pins 26 at the opposite sides of the nose to again positively position the associated transmission with which the latter is in mesh.

From the foregoing, it is apparent that each of transmission gears 24, 24a and 24b can be displaced through only one tenth of a revolution for each complete revolution of the dial disposed to the right thereof, as Viewed in the drawings, thereby to prevent jumping of inaccurate indexing of the driven dials, that is, excessive angular displacement of the latter and resultant inaccuracies in the total, when the manipulated dial is quickly rotated to provide a substantial impact between its driving abutment 27 and the pins of the adjacent transmission gear. In operating the above described calculator, .dials 15, 15a, 15b and 15C are manipulated, by engaging a stylus or pencil in pockets 19 exposed at the circular slots 20, until the numeral on each of the dials is exposed at the related opening `18 of top wall 12 of the casing. In effecting the addition of two numbers, for example, the numbers 789 and 252, a pencil or stylus is engaged in the pocket 19 of dial 15b registering with the numeral 7 of the series appearing on top wall 12 along the outside of circular slot 20, and dial 15b is rotated, in the clockwise direction, until the pencil or stylus strikes against stop 21.' Such rotation will expose the numeral 7 on dial 15b at the related opening or window 18. The dials 15a and i are similarly manipulated to expose the numerals gear and the dial 8 and 9, respectively, at the related openings 18 of the top wa1l.- Then, dial '15b is further manipulated, in the clockwise direction, by inserting the stylus or pencil in the pocket 19 thereof registered with the numeral 2 at the outsidey of -the related circular slot and rotating the dial until the pencil or stylus again contacts stop 21. Similarly, dials 15a and 15 are again manipulated, in the clockwise direction through angular displacements Ifrom the outside numerals 5 and 2 of their respective circular slots to the respective stops 21, corresponding to the addition of 52 to the preceding total, whereupon the numbers exposed at the several windows 18 give the nal total of 1041. v

If, for example, it is then desired to subtract 333 from the above total of 1041, a pencil or stylus is engaged in the pocket 19 of each of the dials 15b, 15a and 15 in radial registration with the numeral 3 of the series of numbers extending along the inside edge of the related circular slot 20, and the several dials are then rotated in the counter-clockwisev direction until the pencil or stylus comes `into contact with stop 21. Such counterclockwise rotation of the dials 15b, 15a and A15 causes angular displacement of dial 15C to a position in which the numeral 0 thereon is exposed at the related opening 18, while the numerals 7, 0 and 8 of the dials 15b, 15a and 15, respectively, are exposed at the related openings or windows 18. Thus, the described calculating device' can be employed to obtain the solutions to problems of addi-tion and subtraction wherein the result does not exceed 9,999. having greater numerical results can be obtained merely by employing a calculating device having a suitablyV larger number of dials and associated accumulating mechanism arranged successively in the manner described above and illustrated in the drawings.

From the foregoing, it is apparent that a calculator embodying the present invention includes a casing, an indi-y cating and manipulating dial for each digit of the numerals involved in a calculation, a detent spring 28 `for each pair of dials in the assembly, transmission gears numbering one less than the number Vof dials in the assembly and a pawl lfor each of the transmission gears. Thus, the calculator is formed of a casing and assemblies of only `four diferent kinds of parts, the casing and such parts, with the exception of the spring detents, being easily molded or otherwise formed of suitable plastic resin materials. Further, all of the Vabove mentioned parts are assembled lfrom above on the shafts or parts which are normal to the bottom wall of the casing and integral with the latter so as to facilitate the inexpensive molding of the casing and mass' production of the calculator.

While a particular embodiment of the invention has been described in detail herein and illustrated in the accompanying drawings, it is to be understood that the invention is not limited to that precise embodiment and that various changes and modiiications may be effected herein, by one skilled in the art, without departing from `the scope or spirit vof the invention as defined in the appended claims. y

What is claimed is':

1. A calculator comprising a plurality of dials rotatf ably mounted in a row and each corresponding to a digit in the numerical result of a calculation, accumulating means co-acting between adjacent 4dials to effect accumulative angular displacement of one of the adjacent dials in response to rotation of the other, said accumulating means including a transmission gear rotatably mounted between said adjacent dials, at least one of said adjacent dials having a gear mounted thereon, said gear of only one of said dials being in mesh with said transmission gear,

said transmission gear having a circularly arranged series n of pins projecting therefrom, a driving abutment on said other dial following a circular path into which said pins project so that, upon each complete revolution of said It is apparent that the solutions to problems Y other dial, said aburtmentengages one-of said pins to drive the latter out ofl said circular path thereby to angularly` displace said transmission gear and said one dial,'and` control means acting on said transmission gear and' actuated by said other'dial to limit the angularidisplacement of said one dial during each complete revolution or" said other dial, said control means including a rockably mounted pawl having a nose at one end engageable between two adjacent pins ofsaid series of pins on the related transmission gear to rotationally position the latter, said nose having, inclined side edges so that said nose can be movedv radially out of the path ofl said pins by riding of the pins against said side edges when said transmission gear is angularly displaced through the action of said driving abutment onione of said pins, and cam-like projections on the periphery of said other dial engageable with said pawl to rock the latter in the direction again projecting said nose between two adjacent pins upon release of said drivingl abutment from said one pin, said cam-like projections including a irst projection followed circumferentially by a second projection, said second'projection being radially larger than said tirst projection so that contact of the latter with said pawl effects partialreturn of said nose to a position projecting between said pins thereby to prevent over-running of said transmission gear, while subsequent contact of said second projection with the pawl completes the return of said nose to its position between adjacent pins wherein the latter contact said inclined side edges of the nose to positively position said transmission gear and said one dial.

2. A calculator according to claim l; wherein said camlike projections include two circumferentially spaced apart sets of rst and second projections with said rst projection of one of said sets circumferentially preceding the second projection of said one set in one direction of rotation of said other related dial, while said first projection of the other of said sets circumferentially precedes the second projection of said other set in the other direction of rotation of said other related dial, whereby said pawl is operative to prevent over-running of the related transmission gear when said other related dial is rotated for effecting either addition or subtraction.

3. A calculator comprising a plurality of independently rotatable dials mounted in a common plane on spaced parallel axes, accumulating means co-acting between adjacent dials to etect accumulative angular displacement of one of the adjacent dials in response to rotation of the other, said accumulating means including a toothed transmission gear rotatably mounted between the axes of said adjacent dials, at least one of said adjacent dials having a toothed gear mounted thereon, said toothed gear of only one of said dials being in mesh with said transmission gear, said transmission gear carrying a circular series of spaced indexing elements, a driving abutment on the other of said adjacent dials, said elements projecting into the path of rotation of said abutment so that upon each complete rotation of saidother dial said abutment engages one of said elements to angularly displace said transmission gear and cause it to displace said one dial in the angular direction of the rotation of said other dial, and control means to limit the angular displacement, said control means including a rockably mounted pawl having a nose at one end engageable between any adjacent two of said elements, said nose having a cam surface engaged by an adjacent element upon rotation of said transmission gear to rock said pawl to an inactive position in which said nose is outside the path of said elements, a radial projection on said other dial, the other end of said pawl lying in the path of rotation of said projection When said pawl is in said inactive position, said projection being operative upon said other end to rock said pawl so as to return said nose to an active position between an adjacent two of said elements following each angular displacement of said transmissionl gear by said abutment, said'one dial being rotatable independently of said pawl when said pawl-is l gear rotatably mounted between the axes of said adjacente dials, at least oneof said adjacent dials having a toothed gear mounted` thereon, said toothed gear of only one of said dials being in mesh with said transmission gear, said transmissiongear having a circularly arranged series ofr spaced indexing elements thereon, a driving abutment on the other of said adjacent dials, said indexing elements' projecting into the path of rotation of said abutment-so; that upon each complete rotation of said other dial saidabutment engages one of said elements to angularly displace said transmission gear and cause it to displace saidl one dial in the angular direction of the rotation of said other dial, and control means to limit the angular dis placement, said control means including a rockably mounted pawl having a nose at one end engageable between any adjacent two of said elements, said nose having cam surfaces at opposite sides thereof, one of said surfaces being engaged by an adjacent indexing element upon rotation of said transmission gear in either direction to rock said pawl to. an inactive position in which said nose is outside the path of said pins, said other dial having a plurality of radial projections thereon and a recess between said projections to receivethe other end of said pawl when said'pawlis rocked to inactive position through a displacement of saidtransmission gear by said abutment, at least one of said' projections being operative upon said other end .to rock said pawl so as to return said nose to an active position between an adjacent two of said elements upon the rotation of said other dialin either direction beyond the point of action of said abutment, whereby digits may be added by rotating either of said adjacent dials in one direction and may be subtracted by rotating the same in the opposite direction.

5. In a calculator, two circular dials adapted to carry digits on one side and mounted in a common plane for independent rotation on spaced parallel axes, a gear on one of said dials, a rotary transmission gear meshing with said dial gear to rotate therewith, acircular series of spaced indexing elements on said transmission gear, the other of said dials carrying an abutment rotatable into the path of said elements to displace said elements and thus index said transmission gear and said one dial, a projection on said other dial in angularly spaced relation to said abutment, and a retainer' rockably mounted for movement between an active position in which-one of its ends lies between two adjacent indexing elements onsaid transmission gear and an inactive position in which said one end lies outside the path of elements on `said transmission` gear' and the other end lies in the path of said projection, said retainer being moved to said inactive position by each indexing movement of said transmission gear and being returned to said active position by said projection upon each complete rotation of said other dial.

6. In a calculator, two circular dials adapted to carry digits on one side and mounted in a common plane for independent rotation on spaced parallel aXes, a gear on the underside of one of said dials, a rotary transmission gear lying in ythe plane of and meshing with said dial gear to rotate therewith, a circular series of spaced pins projecting upwardly from said transmission gear, the other of said dials carrying on its underside an abutment rotatable into the path of said pins to displace said pins and-thus index said transmission gear and said one dial, a radial projection on the periphery of said other dial in angularlyspaced relation/to said'abutment, and a re- 2,7971??? Q i0 tainer having cams at its opposite ends and rockably References Cited in the le of this patent mounted for movement between an active position in UNITED STATES PATENTS which one of its ends lies between two of said pins and l .d g/hliolechon upon each Comp @te rotalwn 0f Sal lo 2,533,443 Farbman Dm 12, 1950 2,541,463 Cummings Feb. 13, 1951 

